Electron density structure measurements with scattered intense laser beam

TL;DR

This paper presents a novel optical diagnostic technique using scattered intense laser light to measure electron density structures and velocity distribution functions in laser-plasma interactions, providing insights into plasma behavior.

Contribution

Developed a new optical method to image electron density and velocity distribution structures in laser-plasma experiments using polarized scattered laser light.

Findings

Polarization ratio indicates laser-driven electron density structures.

Imaging reveals electron velocity distribution features.

Pre-pulse effects alter the electron density structure.

Abstract

Short-pulse intense lasers have the potential to model extreme astrophysical environments in laboratories. Although there are diagnostics for energetic electrons and ions resulting from laser-plasma interactions, the diagnostics to measure velocity distribution functions at the interaction region of laser and plasma are limited. We have been developing the diagnostics of the interaction between intense laser and plasma using scattered intense laser. We performed experiments to measure electron density by observing the spatial distributions and ratio of horizontal to vertical polarization components of scattered laser beam using optical imaging. The observed ratio of polarization components is consistent with the drive laser beam indicating the observed light originates from the drive laser. Imaging of the scattered light shows the structure of electron density, the zeros moment of electron velocity distribution function, interacting with the intense laser. We observed the change of structure due to the laser pre-pulse that destroys the target before the arrival of the main pulse.